1. Field
The following description relates to a fused ring compound and an organic light-emitting device, and more particularly, to a novel fused ring compound, an organic light-emitting device with improved lifetime (lifespan) that includes an organic layer formed using the fused ring compound, and an organic light-emitting display apparatus including the organic light-emitting device.
2. Description of the Related Art
Organic light-emitting devices (OLEDs), which are self-emitting devices, have advantages such as wide viewing angles, excellent contrast, quick response, high brightness, excellent driving voltage characteristics, and can provide multicolored images. Due to these characteristics OLEDs have been receiving growing attention.
An existing organic light-emitting device has a structure that includes an anode disposed on a substrate, a hole transport layer (HTL), an emission layer, an electron transport layer (ETL) and a cathode that are sequentially disposed upon one another. The HTL, the EML, and the ETL are normally formed of organic compounds. When a voltage is applied between the anode and the cathode, holes injected from the anode move to the EML via the HTL, and electrons injected from the cathode move to the EML via the ETL. The holes and electrons (carriers) recombine in the EML to generate excitons. When the excitons drop from an excited state to a ground state, light is emitted.
A major factor affecting luminescent efficiency of an organic light-emitting device is its luminescent material. Fluorescent materials are widely used as light-emitting materials, and there is also an increasing use of phosphorescent materials that is capable of improving light-emitting efficiency up to four times based on theoretical electroluminescence mechanisms.
To lower consumption power of an organic light-emitting device, power efficiency of the organic light-emitting device may be increased. According to the relationship “power efficiency=(π/voltage)×current efficiency”, reducing the voltage may lead to high power efficiency. In practice, an organic light-emitting device using a common phosphorescent (host) material such as BAlq or CBP may have a considerably higher current efficiency, but also have a higher driving voltage, as compared with an organic light-emitting device using a fluorescent material, and thus is not advantageous in terms of power efficiency.
Organic light-emitting devices using such an existing host material are also not satisfactory in terms of lifetime, and thus there is a need for development of a more stable host material with improved characteristics.